Invoice Workbench form behavior against entry of Invoice Withholding after validation

Hi all,
Please confirm the system behavior if an invoice is made, validated, accounted, & approved without any entry of Withholding Tax Code against Invoice Withholding Tax filed. After this, user enters/select respective withholding tax code in Invoice Withholding Tax filed. Shall system go to Re-validation &/or Re-approval state?

I expect that system should go to Re-validation &/or Re-approval state.

Practically when I processed the invoice with all steps of validation, accounting, & approval. Then entered/selected respective withholding tax code in Invoice Withholding Tax filed and Saved the record. System neither changed its validation/approval status nor generated the withholding tax line accordingly to %age of tax code.